Soot from Europe's rapid industrialization in the last 1800s to 1900s most likely caused glacial retreat in the Alps.
The rapid melt took place between the years of 1860 and 1930, which is classified as the end of Europe's "little ice age," a University of Colorado at Boulder press release reported.
The ice retreated an average of about one kilometer (0.6 miles) even though the temperature dropped about 1.8 degrees Fahrenheit. Scientists have long puzzled over this contradiction.
"Something was missing from the equation," Thomas Painter, a snow and ice scientist at NASA's Jet Propulsion Laboratory and lead author of the study, said.
The research team suspected the changes had something to do with Europe's "powerful economic and atmospheric transformation spurred by industrialization," the press release reported.
Coal burning was at the top of the researcher's list of possible causes of the glaciers' rapid decline. Burning coal shoots huge spurts of black carbon into the air, which has been linked to climate change.
When coal coats the surface of glaciers it makes them more likely to absorb the Sun's rays, which could lead to a massive ice melt.
The team studied ice cores drilled from the high points of several European glaciers.
"By measuring the levels of carbon particles trapped in the ice core layers and taking into consideration modern observations of the distribution of pollutants in the Alps, they could estimate how much black carbon was deposited on glacial surfaces at lower elevations, where levels of black carbon tend to be highest," the press release reported.
The team also ran computer models that outlined glacial behavior. They found that when they included the impact of carbon into the models, the rate of glacial decline during that chilly period made sense.
"This study uncovers some likely human fingerprints on our changing environment," Waleed Abdalati, Director of the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, said. "It's a reminder that the actions we take have far-reaching impacts on the environment in which we live."
